Oil burner suction draft control



May 2, 1939. R, rA sMn'H 2,156,359

OIL BURNR SUCTION DRAFT CONTROL Filed `April 19, 1937 `f5 SheetS-Sheet l MMUHULLJVLLM R. T. SMITH May 2, 1939.

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Filed Aprilv 19, 1937 lf. M rl 3 n0 0 9 .y ,/1 0 f |l .J flu f w on L a MH, wwl a l www; ,6 /5 a r .,0 r u May 2, 1939.

R. T. SMITH O IL BURNER SUCTIQN I`JRAFT CONTROL Filed April 19, 1957 5 Sheets-Sheet 3 Patented May 2, -1939 UNITED 4s'lxrrifzs OIL BURNER. SUCTION DRAFT CONTROL Robert T. Smith, Baltimore, Md., assignor to Sherwood Brothers, Inc., a corporation of Maryland Application April is, 1931, serial No.,1s7,.7o4

2 Claims.

The invention relates to oil burners and particularly to the automatic control of the fan draft or primary air whereby a single adjustment ofthe draft control to the quantity of oil -fed l from the nozzle 'effects automatic regulation of the draft, giving exactly the right amount of primary air to support the combustion at all times. The control ofthe invention further com.

pensates for the fluctuations of the-fan, elimil nating the pulsations of the iiame which are partly or Wholly due to such fluctuations.l These `pulsations are one of the sources of noise in oil burner operation and tend to reduce eiliciency. While these incidents to oil burner operation have been generally recognized as objectionable, their correction has not been previously accomplishe in a satisfactory manner.

The apparatus has the further advantage that it provides increased capacity of adjustment of -the draft control Within a relativelyl small space, contributing to the comp'actness of the apparatus and avoiding the necessity for a spring or a long projecting counterweight lever.

The apparatus of the invention in the forminv I2li which it has been practiced includes a suction chamber on the intake side of the fan, the admission of air to which is controlled by. a balanced shutter which determines the air supply to the chamber and tothe fan. In this way the fluctuations of the fan are compensated and the pulsation of the flame eliminated or reduced.

This chamber preferably encloses the oil pump and has'the effect of reducing the noise transmitted to the dwelling apartment heated by the apparatus, both as to the noise of the oil pump and that resulting from the fan, which are important elements contributing to the noisy opera.-

tion which has been found to offer resistance in connection with the sale of oil burners.-

In the accompanying drawings, I have illustrated 1a draft control and suction chamber embodying the features of the invention together with so much of van oil burner apparatus as is'` automatic suction control shutter and counterweight. M Figure 2 is a view looking at the same from of which is used to indicate the same or similar (c1. 15s-2s) l v the left in Figure 1, 'the burner tube being broken away.

Figure 3 is a fragmentary section on the plane of the vaxis of the suction chamber showing the details of the draft control, the weight being 5 broken away and shownpartly in elevation and the Weight and shutter being shown in dotted lines in an open position.

Figure 4 is a section on the line 4-4 in Figure 1.

Figure 5 is an. elevation corresponding to Figure 3, showing a modied form of draft control.

Figure 6 is a fragmentary section of the nozzle and of the burner end of the tube.

Referring to the drawings lby numerals, each 15 parts in the different figures, the construction shown, which is regarded as the preferred form, considerable variation as to detail being contemplated, comprises a burner tube I, fan housing 2,

a fan or rotary blower 3 which is preferably of 20 the Sirocco type, an electric motor 4 which is supported `on the fan casing with its axis in line with the axis of thefan, the motor shaft being connected to the fan to drive the same'. The

, fan 3, as shown, is of the type having a central 25' ing on the left side as seen in Figure 1 at 1, and 30 the suction chamber 8 shown in lelevation in Figure 1 is secured to the fan casing in and around the'opening 1.

In. the form shown, the throat 9 of the suction chamber 8 is provided with a tapereddischarge 35 mouth I0 which projects into the fan housing l2 and has a circular outer peripheral seating surface II which fits in the opening 1, the throat 9 having a circular flange at I2 at the outer side of the seat II. The flange I2 rests upon and ts 4o -the outer at surface of a circular boss I4 which 'surrounds the opening 1, being formed on the fan casing 2.

The seating surface II, the inner surface of the openingl, and the contacting surfaces of the 45 flange I2 and the -bossv I4 are preferably'iinished to make a good contact; and the suction chamber 0, or more particularly the throat 9 thereof,

is secured to the'bossl I l in any -suitable manner,

as by means of bolts I5.

The suction chamber 8, as shown, is formed in two sections- I6 and I1 which are lapped and joined vin any suitable manner, as by rabbeted joint I9, being secured together by means ofscrews I8 passing through the overlapping portions of the two sections at the joint I9. 'Ihe main section i6 of the chamber is shown as vslotted longitudinally at 20 adjacent the joint, the slot having an open end at the outer edge 2i of the main section i6 of the casing and being for a purpose to be hereinafter described.

I'he section i1 of the suction chamber 8 in the form shown is provided with a pump supporting ring 22 adjacent the throat, the said ring having its axis in line with the fan axis. The ring 22 is shown as formed integrally with thecasing wall, being supported by radial struts 24 which may have strengthening webs 25. Between the struts 24 there are sector shaped openings 26 for the suction air as it leaves the chamber 8 and passes through the throat 9 and mouth i0 to the intake of the fan 3.

Figlne 1 also shows the oil pump 21 which is supported by means of its bearing boss 28 ywhich lits in the ring 22, the pump shown being of the gear type driven by the shaft 5 which `lis connected to the center of the fan 3 and is driven by the motor 4.

The oil is passed from the pump to the burner tube by way of the pump discharge pipe 29, being fed to the pump by way of the suction pipe 30. Both pipes 29 and 3i) are passed through the plate 33 which covers slot 20, being secured to the outside of the casing. in any suitable manner, as by means of bolts 34. Suction' pipe 39 is connected to the source of oil supply not shown.

When the section i5 of the casing is removed 'as hereinafter described, as for adjustment of the oil pump or cleaning the strainer, the bolts 34 which hold the plate 33 in place are removed and-the slot 20 releases the pipes as the section I 6 is'withdrawn. Y

The sectiori i6 of the suction chamber is, provided at its end remote from the 'fan housing with an opening 35 wllich is preferably in line 'with the fan axis and concentric therewith, the 'opening 35 being preferably circular. This location of the opening is subject to change, as is also the fan and arrangement of the suction chamber.

As shown, the'opening 35 is 'provided with an internal peripheral flange 36 and a balanced suction draft shutter 31 is pivotally mounted in the opening, being supported by andon a horizontal pivot 38 which is seated at its ends in the walls of the opening 35 as best shown in Figure 2 which shows adjustable bearing members 39 that engage the ends of the pivot, being threaded in openings 40 to provide for taking up on the Important features the provision of the balanced shutter 31, giving a balanced control of the suction air with'means for adjusting the same to the quantity of oil fed from the nozzle, whereby theprimary air'is automatically regulated to the supply of oil fed from the nozzle so that a single adjustment of the air supply for any particular adjustment of the fuel serves to maintain constant proportions of the mixture of oil and air as thus adjusted, and the balanced shutter, together with the suction chamber, has the further important effect of Icompensating for uctuations of the fan, maintaining these proportions and further overcoming the tendency to .pulsation of the iiame with the accompanying noise and loss of efficiency. Except for its compensating actionvin connection with fan fluctuations, the position of C of the invention relate to' the shutter isl constant foreach adjustment of the control.

In the form shown, theshutter 31. is counterbalanced by means of a weight which avoids the variation of tension and consequent loss of adjustment due to a spring control.

The weight 45 in the preferred construction Shown is in the form of a short cylindrical cup. As shown, the weight is provided with an adjusting screw 46 which is arranged in line of the axis of the cup, having its end 41 secured in the bottom of the cup at the center, the screw y46 being for most of its length inside the cup and concentric with the walls 48 thereof.

The screw 46 in the form of the invention shown provides an adjustment of the weight 45 in the direction of its axis, being threadedly engaged with a hub 49. through which the screw is threaded in the direction of a diameter of the hub. The hub 49 is in turn pivotaliy mounted .at 56 between thearms 5l) of a bracket 5l shown as supported onthe outer section I6 of the suction chamber 8 and preferably on the boss 52 which surrounds the shutter opening 35. Preferably the bracket is located at the top center above the Iopening 35 and projecting outwardly beyond the opening.

l' In the form shown, the hub 49 has a substanhorizontal, so that as the bottom of the shutter swings toward the fan the center of gravity of the weight is raised, thus opposing the downward tendency of the weight due to gravity to the tendency of the shutter to open in response to the suction of the fan, it being apparent that the center of the shutter area and hence the center of effort of the suction as appliedto the shutter tending to open the same, is well below the pivot 38, and the contact of the lever 53 with the shutter at 54 is above the pivot. 'It is essential that the moment of the downward tend@- ency of the weight be applied to the shutter in opposition to the'moment of the suction as applied to said shutter, both moments being taken about the pivot 38 as a center. It is alsov an important element contributing to the useful operation of the device that the thrust of the suction against the shutter is gradually reduced as the shutter opens, providing for balancing in a certain position determined by the lever arm of the weight and the degree of suction which is constant except for slight iiuctuations compensated by the shutter.

Itv should be noted in this connection that the ange 35 which acts as a stop to locate the shutter in the position in which it closes the opening 35 is discontinued at 35' just below the pivot 38,' permitting the shutter to swing from closed to open position. Y

It is' of interest as contributing to the compactness of the apparatus Vby providing a conveniently short adjustment of the balance weightY as, theplvot 5I being adjustable within the cup 75 so that the center of gravity of the weight 45 can be adjusted in close proximity to the pivot. The Walls 48 of the cup near the rim 55 and on the righthand side of the center of gravity in Figure 1 have, in certain positions when this rim portion is on the opposite side of lthe pivot from the Acenter of gravity, a counterbalancing effect as to the weight. With this arrangement in ,the positions'referred to where the center of gravity is near the pivot 56, a slight adjustment of the weight in either direction due to the counterbalancing effect of the rim portion 45 gives a' relatively considerable change or the moment of the weight about the pivot 56 and a consequently considerable change of the counterbalancin-g effect of the weight on the shutter 31 and a corresponding change of the balanced position of the shutter.

In the form shown, this adjustment is performed by rotating the weight 45 and thus turning the screw'46 relatively to the hub 49, mov- -ing the weight in the direction of the axis of the screw andin'a radial direction as to the hub- 49 and the pivot 56. The weight 'may be otherwise arranged to'give a counterbalancing effect and a self-counterbalancing effect which is of great advantage ingiving a short adjustment from wide open to slightly open positions of the shutter.

In Figure 5, I have shown a modified form of counterbalance weight 45' which is provided with a counterbalancing ring lill` fitted to the voutside of la cylindrical weight and capable of adjustment in the direction of the axis of the weight and the diameter of the pivot 56 whereby the self-counterbalancing eiect referred to may be considerably increased without any'increase ofl the over-all dimensions of the ,weight lever in the direction of the axis of the fan. It will be understood that other methods of changing the .position of the center of gravity of the weight may be employed. The ring 60 may be used either to partially counterbalance the weight or to increase its-moment about pivot 56, depend'- "ing'upon its relation to the center of gravity of the weight.

In order to increase the sound-deadening efvfect of the chamber, both as to the operation of the fan and the pump and any noise which may result from the flame, the suction -chamber 8 has been shown as provided withv a lining 58- of felt or similar material, and it will also be noted that in order to give access to the pump bearing 59, the throat 9 has been slotted at 63 to admit a wrench or key and this slot is provided with a removable cover 64.

In operation, the quantity of oil discharged from the fuel nozzle 65, within the burner tube I, having been regulated either by changingthe size of the nozzle or adjusting the pump valve 24" to give the pre-determined consumption of oil, the burner being. started, the counterweight 45 is adjustedby'the service man to cause the shutter 31l which is opened in response to the suction of the fan, to admit exactly the right quantity of air to give the most eilicient combustion. When this adjustment has been at tained, the screw 66 seated in the hub *49 and bearing on the weight-adjusting screw 46, which is also the lever arm, is tightened-to hold the adjustment, the apparatus'being thus placed in condition to run for an indefinite period without further adjustment. In the operation of the burner, the shutter 31 is automatically opened to balanced position by the suction of the fan and held open during operation to just the right degree, which is constant in the absence of iiuctuations of the fan, giving exactly the quantity of air necessary to support combustion most efciently, as. determined by the service man. If the oil supply is changed, the adjustment of the counterweight is changed, giving a different shutter opening adapted to admit the right amount of air for the new adjustment of the oil supply. In case of fluctuations of the fan, it is found that to such fluctuations the shutter -responds with a relatively slow equalizing effect which breaks down the tendency to'pulsations of the flame, giving uniform and quiet combustion; The motion of the shutter at these times is slight, and whenv the burner stops it closes. The suction chamber 8 is found to afford important assistance in and to the e'qualizing effeet of the balanced shutter by providing a sufcient volume of air between the -shutter and the fan to assist in the dampening eiect on the fan uctuations already referred to; and it is also of importance that, the oil pump and the fan suction being thus enclosed, the noise which is transmitted to the apartment heated by the burner is greatly reduced and this reduction of noise is assisted by the provision of the felt orsimilar lining indicated at 58.

I have thus described an oil burner suction control .embodying the features of my invention in the preferred form, the description being specific and in detail in order that the manner of constructing, applying, operating and using the same maybe fully understood; however, the specific terms herein are used descriptively rather than in a limiting sense, 'the scope of the invention being defined in the claims.

' `What I claim as new and desire to secure by Letters Patent is:

1. In an oil burning apparatus comprising a rotary air blower, a housing encasing said blower, a motor located adjacent one side of said housing for operating said blower, said blower housing having an air inlet through the opposite side thereof a'nd adjacent the axis of said blower, a muling chamber supported about and outwardly from said air inlet, an opening in the opposite end of said casing, an oil force pump wholly located within said chamber and lying between the said opening and the air inlet to said blower housing, and means for receiving the air from said blower and conveying the same to a combustion chamber.

2. In an oil burning apparatus comprising a rotary air blower, a housingencasing said blower,

ing for operating said blower, said blower housing having an air inlet through the opposite side thereof and adjacent the axis of said blower, a muiing chamber about and outwardly from said air inlet, an opening in the opposite end of said casing, means for automatically regulating the size of said opening, an oil force pump-wholly located within said casing and lying between the said opening and the air inlet to said blower housing, and means for receiving the air from said blower and conveying the same to a combustion chamber. p

ROBERT T. SMITH.

.a motor located adjacent one side of said hous- A 

